|Occupation||High School Student|
|Base of Operations||Karakura Town, Japan, Human World|
|Education||Karakura High School|
Shinji is a freshman in Karakura High School.
Shinji is a small teenage boy with brown hair. He has large brown eyes and wears the school kendo uniform.
Shinji is initially a coward, however, thanks to Ikkaku Madarame, he is able to gain enough courage to avenge the defeat of his seniors. While Shinji trains, Ikkaku noted that Shinji's eyes burned with the desire to become stronger.
During a walk to his home, he was attack by members of the Kotei Academy Kendo Club, but was defended by his senior members of his own kendo club. The next morning, during the club's meeting, he along with the rest of the freshman members of the team were selected by the class president to participate in a match against the opposing school.
Mizuho requested Ikkaku's help in training the team and the latter begun an intensive training regiment. Shinji and the rest of his team's training consisted of pulling Ikkaku in a carriage full of boulder rocks, bunny hops up a temple stairs, practicing their strike upside down and carrying a heavy rock while sitting down tied in a rope. With the thought of winning, Shinji endured the harsh training, and while the rest of team was too tired, Shinji continued matching swords against Ikkaku, who noted that he had spirit, even though he originally appeared to have the least potential. Due to Ikkaku's intense training proving to be to much for the team to handle, and with the exception of Shinji, the team ended more injured than the other members whom they were replacing.
Mizuho convinced Ikkaku to get some people to replace the other members. Shinji volunteered to remain in the team. After failing to recruit Yumichika Ayasegawa and Rangiku Matsumoto into their team, Shinji, Ikkaku, and Keigo Asano wonder what to do. Shinji remarks that if only he had gotten out of the situation faster they wouldn't have this problem, but Ikkaku tells him to stop whining and remember that the reason he got those injuries was because he ran away and he didn't stand his ground like a man. As Ikkaku takes his leave, he tells them not to worry about finding new team members, to which Keigo asks if he is going off to make new friends. Ikkaku simply replies by calling him an idiot.
The day of the match, Shinji witnesses Ikkaku attempt to convince Tōshirō Hitsugaya into entering the match. With Ikkaku, Tōshirō, Renji Abarai, and himself, Shinji watches as Keigo is forced to join the team.
With the match line up decided and Shinji being fourth in line, Ikkaku tells him that if he doesn't win, Ikkaku will and not to worry. Shinji then is encouraged to win his fight with Ikkaku telling him that it would be great if he won his match. As his turns comes up, the team is sitting at two wins and one loss, Ikkaku once again reminds him that it would be great if he won and not to worry, as he would win if Shinji didn't. Shinji faces his opponent, and as he gathers courage, he delivers the winning blow and gets the win necessary for his team's victory. Ikkaku congratulates him on winning the match and Shinji watches Ikkaku demand his turn, and consequently defeats the entire opposing team.